From: David Miller <davem@davemloft.net>
To: benh@kernel.crashing.org
Cc: ebiederm@xmission.com, suresh.b.siddha@intel.com, matthew@wil.cx,
linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
grundler@parisc-linux.org, mingo@elte.hu, tglx@linutronix.de,
jgarzik@pobox.com, linux-ide@vger.kernel.org,
jbarnes@virtuousgeek.org, rdunlap@xenotime.net,
mtk.manpages@gmail.com
Subject: Re: Multiple MSI, take 3
Date: Sun, 13 Jul 2008 17:44:57 -0700 (PDT) [thread overview]
Message-ID: <20080713.174457.82768245.davem@davemloft.net> (raw)
In-Reply-To: <1215994659.7549.227.camel@pasglop>
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Mon, 14 Jul 2008 10:17:39 +1000
> On Sun, 2008-07-13 at 16:29 -0700, Eric W. Biederman wrote:
> > Ben. Multi-MSI is a crap hardware design. Why do you think we have
> > MSI-X?
>
> I know and I agree. Which is why I'd rather keep the SW crap totally
> local to the MSI support code and not add new concepts to the generic
> IRQ API such as sub-channels, for which it's really not ready for imho.
>
> They -are- separate IRQs, just badly implemented. Besides, a large part
> of the problem is purely due to the typical x86 implementation of them,
> since for example, on most PowerPC's (and possibly other archs), they
> tend to land in the PIC as normal sources, and as such benefit from all
> the "features" of such interrupts like HW masking, affinity control,
> etc... at the PIC level.
This is how it works on sparc64 too.
The x86 system designers decided to implement multi-MSI in an
inconvenient way, it is not a "crap hardware design", merely
some (unfortunately common) implementations of it happen to be.
next prev parent reply other threads:[~2008-07-14 0:44 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-11 0:57 Multiple MSI, take 3 Matthew Wilcox
2008-07-11 0:59 ` [PATCH] PCI MSI: Replace 'type' with 'is_msix' Matthew Wilcox
2008-07-11 0:59 ` [PATCH] PCI: Add support for multiple MSI Matthew Wilcox
2008-07-11 8:28 ` Hidetoshi Seto
2008-07-11 9:45 ` Matthew Wilcox
2008-07-12 3:45 ` Benjamin Herrenschmidt
2008-07-11 1:00 ` [PATCH] Rewrite MSI-HOWTO Matthew Wilcox
2008-09-26 6:42 ` Grant Grundler
2008-07-11 1:00 ` [PATCH] AHCI: Request multiple MSIs Matthew Wilcox
2008-07-11 1:00 ` [PATCH] x86-64: Support for " Matthew Wilcox
2008-07-11 4:50 ` Kenji Kaneshige
2008-07-11 8:50 ` Matthew Wilcox
2008-07-14 1:08 ` Kenji Kaneshige
2008-07-11 10:06 ` Multiple MSI, take 3 Eric W. Biederman
2008-07-11 10:23 ` Matthew Wilcox
2008-07-11 10:32 ` David Miller
2008-07-11 10:41 ` Matthew Wilcox
2008-07-11 11:05 ` Eric W. Biederman
2008-07-11 11:34 ` Eric W. Biederman
2008-07-11 12:17 ` Matthew Wilcox
2008-07-11 15:10 ` Matthew Wilcox
2008-07-11 21:59 ` Suresh Siddha
2008-07-11 22:59 ` Eric W. Biederman
2008-07-11 23:15 ` Suresh Siddha
2008-07-11 23:59 ` Eric W. Biederman
2008-07-12 3:52 ` Benjamin Herrenschmidt
2008-07-12 4:41 ` Eric W. Biederman
2008-07-12 7:36 ` Benjamin Herrenschmidt
2008-07-13 22:30 ` Eric W. Biederman
2008-07-13 22:44 ` Benjamin Herrenschmidt
2008-07-13 23:29 ` Eric W. Biederman
2008-07-14 0:17 ` Benjamin Herrenschmidt
2008-07-14 0:44 ` David Miller [this message]
2008-07-14 2:03 ` Eric W. Biederman
2008-07-14 3:19 ` David Miller
2008-09-26 5:30 ` Jike Song
2008-09-27 19:04 ` Matthew Wilcox
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